PROJECT SUMMARY/ABSTRACT Cancer, an often incurable and progressively disabling condition, is frequently characterized by mutations caused by chromosomal rearrangements. However, many of these mutations are poorly understood, and consequently, the availability of novel therapeutic regimens is limited. The molecular targets of Myc, a transcription factor whose oncogene has been marked as one of the most highly amplified oncogenes in many human cancers, has mystified scientists for decades. Due to the difficulty of using targeted therapies to limit Myc oncogene addition, recent studies have explored the concept of non-oncogene addiction through synthetic lethality to identify Myc's oncogenic support pathways. Specifically, large-scale RNA interference (RNAi) screening was used to successfully identify unique genes that are synthetically lethal in Myc-transformed cells, namely the core spliceosomal factors. Although these were landmark findings, it remains unclear if MYC overexpression is maintained solely by the spliceosome or if other RNA-binding proteins (RBPs) are responsible for detrimental changes in splicing patterns in these cells. This project involves using leading edge technologies to perform large-scale functional assays to identify RBPs that control Myc-dependent survival in cancer. CRISPR/Cas9 screens have been used in the past to overcome many RNAi limitations, and have since been used in various successful genome-scale screens. This proposal will employ a targeted CRISPR screen to identify a common set of RBPs specifically required for survival of both Myc-transformed human mammary epithelial cells and patient-derived cancer cells characterized by elevated MYC levels. Technologies including eCLIP-seq and RNA-seq will be used to identify the physical and functional targets of one candidate RBP. This study will provide feasibility to broadly explore the function of RBPs in many human cancers, which will undoubtedly improve the current understanding of miregulations in the human genome that lead to this devastating disease. Lastly, this study will develop a novel genomic tool extendable to other biological questions, while accelerating cancer genome research by providing a set of synthetic lethal RBPs in various Myc-induced tumor-specific cell lines as clinical validation for targeting RBPs as treatment.!